.app-tab{
  position: sticky;
  z-index: 99;
  top: 50px;
  display: flex;
  background-color: $theme;
  >a{
    position: relative;
    flex: 1 1 auto;
    text-align: center;
    height: 44px;
    line-height: 44px;
    color: #fff;
    &.router-link-active{
      span{
        padding-bottom: 3px;
        border-bottom: 2px solid #fff;
      }
    }
  }
}